What is white algae?

Many types of algae invade fish tanks and the white algae is just one of them. It usually looks like a web or a slick film and often spreads pretty quickly once it gains a foothold. It has the potential to quickly become disgusting and a nuisance. 

White algae usually grows on aquarium rocks, driftwood, ornaments, and so on. It is rarely found on the tank itself.

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What causes white algae?

White algae is caused by the very same conditions that cause all other types of fish tank algae to grow. The conditions are excessive lighting, excess nutrients, and warm water. 

Excessive lighting

Light is the main energy source for algae. Without light, algae cannot grow. They cannot bloom. Many aquarists usually illuminate their aquariums with some sort of aquarium lighting to see their fish and the aquascape they have built more clearly. While this is totally fine, many usually overdo it by not switching off their aquarium lighting. 

Aquarium lighting needs to be done in such a limited way that it does not promote the growth of algae. Alternatively, traditional aquarium lighting fixtures can be replaced by modern ones that are specially made not to grow algae.

Excess nutrients 

Algae eat nutrients from toxic detritus, decaying debris, fish waste, and food waste. If these nutrients become excess in the water, algae will have plenty of food to eat and to multiply. This can lead to a serious infestation. 

The nutrients can become excess when you give your fish too much food and part of it goes uneaten, when there is too much debris and detritus in your tank, and when you do not clean and maintain your tank regularly.

Warm water

Algae only breed and flourish in warm temperatures. Most people have water heaters to keep their tanks warm during cold weather. This may be good for your fish if it is a tropical fish but it is also good for algae and it promotes their growth.

As you can see from the above points, a combination of excessive lighting, excess nutrients and warm water can cause an algal bloom. It can cause white algae to spread throughout your tank.

Why is white algae bad?

Some people say that the growth of algae in fish tanks is not bad or dangerous to aquatic life. That, in fact, it is beneficial because some aquarium fish species like eating algae. This is true. However, it is not the whole story. 

White algae and other types of fish tank algae can indeed be eaten by some aquarium fish. However, this benefit is nothing compared to the danger posed by algal blooms, especially at night. 

At night, algae consume oxygen and release carbon dioxide. If algae are too many in a fish tank, they may cause the concentration of dissolved oxygen to drop to dangerously low levels. And when this happens, it can suffocate your fish and any other aquarium life depending on oxygen (e.g. live plants). So algae infestations are really bad and can lead to the death of your fish and plants.

This is why it is important to know the methods of removing white algae and other types of algae whenever you see them.

Methods you can use to beat white algae and other types of fish tank algae

  1. Algae eaters

Algae eaters are fish, shrimp, and snails that love eating algae. Most algae eaters are very effective and can help clear algae populations very quickly. They can also prevent future algal blooms in your tank since they will quickly eat any algae they spot.

Experienced aquarists keep common plecos in their tanks as algae eaters. Other commonly used fish algae eaters include barbs, Siamese algae eaters, Chinese algae eaters, mollies, American flagfish, and danios. Commonly used snail algae eaters include Nerite snails and Sun snails. 


  • It is a very effective method of removing algae
  • It prevents future algae invasions
  • It introduces a tank mate or tank mates for your fish
  • It provides a spectacle (it is fun to see some fish scavenging and eating algae)


  • It is sometimes difficult to find algae eaters compatible with your fish
  • It is sometimes expensive to buy compatible algae eaters
  1. Multi-stage filter


You can remove algae from your fish tank by getting a powerful multi-stage filter. Aquarium filters are built to trap and remove biological, chemical, and mechanical waste from your fish tank. Algae are mechanical waste. The fact that they can accumulate in your tank means that your filter is most likely not very effective. To change this, you should purchase a more powerful filter that can clean your tank water better. There are many powerful multi-stage filters available online.


  • A powerful filter will eliminate you algae for you 
  • It will keep your aquarium water sparkling clean
  • It eliminates other waste


  • A filter cannot easily detach algae that have embedded themselves on certain surfaces
  1. Manual scraping


Manual scraping is a not very convenient way of removing algae but it is very efficient. This is because, through manual scraping, you can remove everything including the algae that your filter cannot remove.

To remove algae via manual scraping, you should remove your fish and scrape everything in your tank that is not a living them. Scrape the glass, the gravel, the decorations, the rocks, and so on. This will remove algae completely. When you are done, rinse everything with a power spray.

You will need a special algae scraper or pad to eliminate algae using this method. Do not use a rock or a razor blade to scrape algae off your aquarium windows. The two can cause bad scratches that you will not be able to wipe away.

There are plenty of different types of algae scrapers available on the market. They are specifically made for safely scrapping aquarium glass and other aquarium components. They are the best to use for scrapping since they cannot harm your tank or release chemicals or pieces that will harm your fish when you put it back into the tank.  Algae or aquarium scrapers vary greatly in prices. 


  • It is a very efficient method
  • It can cause nothing 
  • It can help you remove all toxic chemicals


  • It is very time and energy-consuming
  1. Ultraviolet (UV) sterilizers


Perhaps one of the most effective ways to diminish and kill excess algae in your tank is to use a UV sterilizer. A UV sterilizer is a special machine built to emit UV light and kill certain micro-organisms. Aquarium UV sterilizers are those that are built to kill algae in fish tanks. By getting a good UV sterilizer from a marketplace such as Amazon, you can kill all algae in your tank and several other micro-organisms and pathogens. In other words, you can make your aquarium water much safer and healthier for your fish.

The UV sterilizers currently available on the market vary widely in prices. Some of them are cheap while others are pretty expensive. Some of them also have additional features and functions. Perhaps two of the best of them are the Green Killing Machine and the Aqua Sterilizer (UV). Both of these machines are very effective at eliminating algae.


  • Aquarium UV sterilizers can eliminate 99 percent of algae
  • They can also eliminate other harmful micro-organisms and pathogens
  • They can do the job automatically and effortlessly 


  • UV sterilizers can be expensive
  1. Water changes

Regular partial water changes are very important in the aquarium world. If you do not do regular partial water changes, toxic wastes will accumulate in your tank. This could lead to the death of your fish and plants.

While water changes are primarily done to eliminate toxic wastes, they also bring the additional benefit of algae elimination. For instance, if you replace 50 percent of the water in your tank with fresh water, then it means you have removed 50% of the algae that were in it.

One important thing to note about water changes is that you cannot change 100% of your tank water in one go. This is because this action will also remove 100% of beneficial bacteria in your tank water. And this is something you do not want to happen. Therefore, you should only do partial water changes to gradually reduce the population of algae in your tank.


  • This method removes toxic waste plus algae 
  • It removes the nutrients responsible for algae growth 
  • It introduces cleaner, safer, and aerated water 


  • This method does not remove 100% of algae 
  • It is time and energy-consuming
  1. Algaecides

An algaecide is a chemical that is specifically made to kill algae. It works quickly to kill off algae and prevent the future growth of algae. There are several different algaecide brands and products on the market. Most of them are very effective and kill algae by either destroying them or suffocating them.

Although algaecides are effective removers of algae, they are usually only used in extreme cases. This is because they are chemicals and they have long term negative effects on fish and plant life. Therefore, if you acquire an algaecide to eliminate algae from your tank, you should only use it like three times at most every year to minimize the potential long term negative effects.


  • Algaecides kill 100% of algae
  • 400;”>They work very quickly 
  • They prevent algal growth 


  • Algaecides can cause long term negative effects

The methods above can help you eliminate algae from your fish tank. However, some of them will not prevent another outbreak from occurring. Actually, there is nothing that can prevent an outbreak from occurring. Nevertheless, there are things you can do to make another algae outbreak unlikely. They include:

  1. Getting better lighting 

As mentioned earlier, excessive lighting will encourage the growth of algae. You can prevent the growth of algae by getting smart lights that you can control through timers or by switching off your aquarium light whenever you do not need it on. Alternatively, you can get an aquarium light that does not encourage the growth of algae.

  1. Avoiding overfeeding 

When you overfeed your fish, it or they will not eat everything. This will result in the accumulation of food waste at the bottom of the tank. This will, in turn, encourage the growth of algae. By avoiding to give your fish excess food, they will eat everything you give them and there will be no nutrients left for algae to feed on and bloom in your tank.


White algae like other types of algae are a nuisance at first and can be very dangerous for your fish. The moment you notice the presence of white algae in your tank, you should remove them using any of the methods listed above. The best one among them is probably manual scrapping. After removing the algae from your tank, you should take steps to prevent another algal outbreak from occurring.